IMO your strategy is very bad.
If you have to wait for Germans to attack in 1941, you will enter war at very significant tech disadvantage. If you overbuild infantry, your officer needs and loses difference due to tech difference would heavilly cripple your ability to attack Wermacht.
Also, the river line defences requires you to give up quite a lot of leadership points, and rivers work both ways, so if you dig on the river line, your opponent does the same.
You need to gain a lot of land doctrine practicals and keep your officer loses low, to be capable of counter-attacking. Otherwise, you will end up eaten peace-meal by high-quality German mobile forces, when you will, eventually have to move from the river line into attack, while they give up ground in some places, to keep your forces occupied.
Managing officer loses is essential for USSR.
If Italy is Human player, it can be a very serious problem for UK, since UK invasion capabilities are severely limited by ports capacities.