If you have the ETN for a part (8 figure number), it is worth requesting it from DS, even if it is not shown on 'Find Spare Parts'. This includes figures (though some Licensed figures are not available this way, but Novelmore figures are). The U.K. System does seem to have very few parts it will not supply, at least for current and recent sets.
Another reason for asking for what you want, even if it's not listed, is because the DS staff do have lists of 'alternative' parts which they can supply (though they do look things up on PlaymoDB to find alternatives too!).
One final tip; don't order spare parts until after Christmas, they only offer a skeleton service at busy times.