Have a look on your fleet and army. UK has huge numbers of both and as such those literally eats up money!
Don't overlook those on your provinces which ain't at Europe but are in India, America and so on. The UK has enormous numbers of troops and ships even in the colonial-world. So it might be better to dissolve some of those, especially in colonial-territory. All the more if there ain't no greater threat anyway.
Fleets & Armies
The UK is a pretty particular exception when it comes down to threats; You as UK can afford the very luxury to not have to have any greater standing armies – thanks to your vast number of allies around the globe! Pretty much no-one in his sane mind would dare to attack you or your land – even if there are no or only small numbers of troops within those lands of yours. So you can dissolve the greater part of your armies and/or fleets without having to worry about anything, since the moment someone would declare war on you, he literally has half the world against him (like Canada, New Zealand, Australia and so on).
Economics
However, it was a time which heavily showed (ultimately) that this allegedly Great Empire didn't really could afford its huge lands, numbers of troops and/or fleets – and it never really did so in the first place. England, especially at that time (and ever since, if you have a look back into history), mostly had to rely upon robbing and looting their British colonial possessions really brutally, Like.no.other™ of any given colonial powers at that time or any time at all.
This imagination of that Great British Empire™ where „the sun never settles upon the whole Empire which spanned the globe“, was (at the core) pretty much always what it actually indeed was: A plain unworkable fantasy of omnipotence and almightiness of some incredibly arrogant and boastful British aristocrats which was continuously celebrated behind and within closed-door conversations of a few grey eminences. From a economic standpoint, UK never neither had the potential nor the economy to operate such a huge empire, especially they never had (or at least showed) the will being able to manage such vast territories.
Live and Let Die
There were other Kingdoms and/or Countries which showed way more remarkable economic prosperity, will and the actual mercantilistic backbone to provide the bare ability to maintain such huge territories. Like the Netherlands, Portugal, Spain or even the German Empire. Especially the Netherlands, Portugal and the Prussian Empire were able to hold, manage and maintain greater territories due to having the economic power (and actual will) to do so.
You can see in history that especially those three Nations not only were able to live in quite some piece with their colonial territories but the colonies could live, grow and thrive alongside their superior protecting power of their 'owners'. Those colonial powers didn't saw their 'belongings' as a land-based gold-mine which needs to be raped by all means and against all odds, but they saw their colonies as an extension to their own soil – and treated them accordingly. That meant that they tried to rather make those regions flourish and prosper, so that those lands/regions shall bring them profit in the long run.
England and (to a way lesser extend) France on the other hand just relied upon despoiling and plunder their 'outer' colonial regions and in fact defended their colonies first and foremost against given local residents with horrific cruelty – and a quite bloody rage if those occupied territories weren't able to deliver the given profitable support that their motherland couldn't live off them. They saw those possessions and their military power as the true-born legitimation to wreck those regions and to live on in clover at their homelands, all that to thrive or prosper at the expense of their colonial regions. It was actually rather a repressive apparatus then a way to hold such colonies in the long run. That's a state which can't exists in the long run (no pun intended) …
The Game
Having said this, within the game and playing as the United Kingdom in particular, you don't really have to worry about your war-chest, your debts or anything being economically manageable – not at all. Since, and as incredible and unbelievable as it sounds, it's somewhat hard-coded into the game that especially UK can't go bankrupt at any time as it gets virtually never-ending borrowings which does not run out. May sound somewhat paradox, it probably is.
So, please feel free to war your way through Europe or even the whole World – nothing really stops you from doing so.
Smartcom
