shape of bath will make no difference other than will it fit , shower fine as long as your house pressure good , some have low pressure which means a crapola shower as it'll be cold but usually no probs . Combi's are great imo . make sure it's level and use around a tube of mastic to stick the bath to the wall then tile then more mastic , many fitters don't bother with the mastic first and many baths have leaks because of this , all in all simple to do . p.s use flexible tap connectors (bath) and speed fittings , avoid compression as this is also what leaks the most (right by tap which you can't bloody get to after ) . Have fun .