Hiya - And Welcome to FOG-dom..
Mines a little 2.0 sport (SWB) and its very tail happy in the wet... But I do drive it like I stole it. Its a weekend toy (rebuilding a 2.2 RS as well), normal - boring Eurobox cars during the week

Anyhoooo - back on subject...
Understeer / Oversteer can be caused by 1 million and 1 different things from tyre pressures - too high, will slip, too low - tyre sidewall will distort and the tread wont remain fully in contact, tyre type - mine is on Muddies.. 80/20 bias - 80% off road, 20% on road - which means there isnt really F1 grip levels.., also there have been mentions in a few threads on here Re Tyre types about AT (All Terrains) losing their effectiveness even with 3-4mm of tread left. My 2.2 RS is on AT's with barely more than 2-3 mm left on it, and its like driving on marbles - so as soon as its better - new tyres..
An old addage about Rear wheel drive regarding corners.. Slow in - Fast out.. Brake in a straight line (ish), get the car lined up and then apply the loud pedal progressively..

erm.. thats the theory.. not - brake, into second, gun it...
Also, the tracking was out on Martha (2.0 Sport) - Cant think how..

I 'may' have lovingly caressed a tree / rock / ditch etc playing in the woods - This affected fuel consumption and the handling was p!ss poor on road, used to 'track' in overbanding, or in the lorry ruts on the inside lane of the motorway. took it in for a 4 wheel alignment (£30 per adjustment, normally 2 needed) and she is now as sweet as a nut - runs straight and true, Until this coming Sunday - (next SE picnic in the woods..

)
As has been mentioned by the people that know with LWB's.. it is a 2 ton car, with a higher centre of gravity and a fair lump of body roll. Slowing down in the corners will certainly help, Tracking checks can be done for free, and double check tyre pressures...
but a fistful of Opposite lock off a roundabout (when safe to do so).. kind of puts a grin on your face..
John