[quote name='matt_citizenbass' post='450138' date='Mar 31 2009, 12:00 AM']i'm currently selling my head and have about £250 or so to spend on a old valve head...
...what are your experiences?[/quote]
I would recommend saving up and then looking for a decent used Ampeg, Mesa Boogie, Orange, Hiwatt, etc.
There's a lot of love for the Orange AD200B Mk.3 here on Basschat and that's a 200W valve head.
I personally use a Mesa Boogie Bass 400+ and it's a real beast of an amp but a Mate has an Ampeg SVT 2 Pro and that is really nice too...
Good luck,
JTB