Please excuse me for not replying to your question, i read it, meant to deal with it and plain forgot, sorry.
I'll have a look at some of the books we have in the workshop and see what's there that could be useful for you.
I learnt engine building as part of my trade.
I'm sure that there are companies down your way which would be glad to take on someone as a Saturday lad, get out and ask them, that's the only way you'll know for sure.
We have two apprentices who attend the National Motorsport Academy at Silverstone for their courses, they both started as Saturday lads.