I get hot water from the kitchen tap, yet the bathroom which is next to the kitchen, the water comes out luke warm... any ideas??
I have a combi boiler & had it repair (I wasn't getting any heat in my radiators) recently, as a temporary fix the engineer said he would jam (? ) something open in side the boiler so I could get heating in the radiators but my water may not get as hot. Now the 1st time I've run a bath the water is luke warm. Puzzled!?

You answered your own question.

((engineer said he would jam (? ) something open in side the boiler so I could get heating in the radiators but my water may not get as hot.))

Get it fixed properly if you want hot water at every tap or carry water from the kitchen tap to the bath tub.