seriously, try the celica. a very *nice* car, its a long way from the bangery stuff you're used to - it'll hold its value - after 10 years it'd still be worth 3k if looked after - a fiester is worth about £3. 1.8 engine isnt too big, but it is very nippy - particularly in 180bhp guise (you can choose 180 or 140). and just fits nicely in your criteria..
http://atsearch.autotrader.co.uk/WWW...00634246865705
i don't know what they're like for size inside - no idea, but you might find em fine. 5 miles of city driving is more than enough to get an engine warmed up, but that does sound like 2,000 cold starts a year (are you sure thats right - thats 6 trips a day, every day??)
otherwise, you seem to like your fords, how about a late puma, same sorta vein as a celica, but a touch smaller.
http://atsearch.autotrader.co.uk/WWW...00633246794266
or, for go-kart handling, the mini can't be beat - i think they're coming into your pricerange now. go for a cooper - quick enough, without holding the cooper s premium
http://atsearch.autotrader.co.uk/WWW...00632101360601