Hi Minni,
If you've not sorted it out yet, e-mail me and I can discuss rates with you.
I'm not touting for work, so please don't get upset miss.moderator, just happy to discuss timescales and details of the job to set expectation.
Costs will be regional. Easiest way to get a quick comparison is to call a few plumbers/tilers and ask tehm for their m2 rate/ unit rate.
I'm a tiler and fit bathroom suites, so happy to discuss anticpated timescales etc with anyone who has a query.
One obvious queston, do the tiles need to come off?
If the existing ones are sound and do not interfere with your new suite, e.g. space restrictions for using taps/fitting bath etc, then the best option would be to overtile, this could save you up to half the cost - the bulk of which would be labour anyway !