Intresting bike, as above go with a thomson inline (?) drop a couple of spacers or run a low rise bar or 0 degree stem, it will help the climbing a bit if that is where you have the seat post normally.
Tyres
have a look at, all on crc website
Maxxis Advantage - FR From £17.99
Tioga Blue Dragon Magnum 66 From £17.99
http://www.chainreactioncycles.com/Models.aspx?ModelID=5464
Tioga Yellow Kirin Magnum 66 From £19.99
used one of these most of last summer, decent tyre, survived the prynees, and i think did well in STW test of tyres
WTB WeirWolf Comp Tyre
no idea what they are like but cheap
WTB Mutano Raptor From £11.00
but one persons tyre recommendation is anothers living hell.
Good luck and tell us howe you go on 
