Lets pencil that in for a start then and see who else can come.
As for getting there: I take my town's train (it's on the Chester/Manchester line) directly to Piccadilly or Altrincham, then catch the tram to Victoria.
Manchester, being a city has plenty of parking spaces, and Victoria station is right next door to a car park (but I don't know how much it would be, given it's a Sunday I don't think it'd be that expensive or busy).
Piccadilly has a proper car park, you could park there then catch the tram to Victoria.
I recommended coming without a stilt-bag. Whilst they're alright for things where you stay in one spot (like CB08) they're a lot of trouble to carry when going around a city centre (I learned the hard way last year, good thing my stilt bag has shoulder straps).