I basically just buy the DVDs when they are on sale on Amazon and rip them to my server.
If they're too expensive I just buy them used on Ebay (since I end up ripping them anyways). SInce they're usually cheaper there.
Hulu has some of the shows but not the entire series' Postman Pat Season 1 13 episodes Danger Mouse 19 Episodes KidsWB has Thundercats and Tom and Jerry (Tales). The problem is that it does not have the entire collection. Just the same 7 -11 episodes that have been up there for years. And since you're in the UK the only way you might get access to the pages I mentioned is through a vpn or dns service.