For Ball Joint Splitters, take a look here: http://www.machinemart.co.uk/shop/search/filter/ball+joint/page/1
I ordered one yesterday as I have to do this very job myself as a result of an MOT failure. That, coupled with a track rod end and exhaust.
The ones that work with a hammer are not very good IMO - it takes a lot of hammer action before the joint comes apart.
I vaguely recall having to use fork type due to lack of room to get the screw type in...
Just had a phone call from the misses saying it has arrived yay pretty quick delivery.
I think I will see about using one of the forked splitters as my dad seems to think he has one, if not its a trip to my local Bennetts as they seem to have them.
Update
So far the swap is on hold until after work I had a go at swapping the idler last night and it proved to be a right bugger to do.
I started off without a balljoint splitter which was partly my fault and my dads as he said he had one then come to use it couldn't find it.
Anyways i got the car up in the air with the wheel off, nuts came off the idler fine but the balljoint is an absolute bastard to get out.
I ended up getting ferried to my local halfords to get the splitter which was the
fork type, these are no use when doing this type of job as the ends are too thick to get under the join to prise the balljoint out and so I am going again to my local halfords to get the smaller jobby which hooks around the balljoint and you wind the bolt in forcing the balljoint out.
Space is also limited under there so in my attempts for the swap i noticed the steering idler mounting bracket when released lower the steering arm giving plenty of room, if had had the right tool it would have been done.
What I found was the fork type splitter is ideal for removing the tracking arms as it goes in the joint where the tracking arm connects onto the centre steering arm.