hope somebody can help I'm fitting a kitchen turned the hot water off

[king of pipes]

just get a professional plumber in bud not a hard job if you know what your doing , you could end up flooding your home

 

[joni os]

In older house very likely feed to HWC will be 3/4" not 22mm. Make sure you have 3/4" compression olives to go with full bore 22mm lever valve. Moving pipe apart to install new fitting could also be problematic as straining pipe against weight of full CWS tank could result in leak at outlet. Work for plumber, or if DIY, drain tank to give plenty of time to sort out unknowns.