I've been happy with Lythgoes mate, they're the dealer I use all the time. The first thing I'd say though is why on earth are you taking it to a dealer if you've no warranty? Far better off going to an independent. If you still want a Nissan name, try PMing Dan on this forum - he's a Nissan independent specialist (used to be a dealer), think he's Blackburn way.
I'd say if an axle is clicking and it isn't sorted it will detoriate and cause premature wear, although I could be wrong.
£220 sounds about right for the P2, Lythgoes do have decent prices.