SOC

I would suggest that unless you have large amounts of money to spend, you should concentrate on a small area of collecting. I have a fairly large collection of pre decimal UK coins and I concentrate on Florins and Half Crowns. The most importatnt thing apart from rarity is the condition of the coin/note and will make a lot of difference to the value. Talk to other collectors and do some research before you start laying money out.
If you should come accross a threepenny bit from 1937 with King Edward VIII
on the reverse please let me know. They were minted in 1936 just before he abdicated and a few got into circulation and are reckoned to be worth 25,000 each, check with your older relatives. I will give you 500 quid for it :p
Good Luck
O.G.