well, it turns out the battery was shot. it showed 12v but the amps were just about zero. i put a new one in (€70) and i'm back in business. i also cleaned up the terminal connectors, earth from the starter to the body, so hopefully that's that.
i should really get my 20 quid back off the mechanic who told me i needed a new starter motor... bastard..
thanks guys..
cheers,
Gareth