The Cycle mechanic said he could fit them to the existing wheels, but
Halfords customer service reckons you can't. This is the bikes spec (below.) Maybe this will help you decide if I can. Thank you!
Approximate Weight (KG): 13kg
Brake Type: V-Brakes
Forks: Steel
Frame Material: Alloy
Gender: Mens
Number of Gears: 21
Pedals Included: Yes
Suspension: Rigid
Wheel Size: 27.5"
Bottom Bracket: Square Taper. sealed
Cassette/Freewheel: 7 speed Screw fit
Chain: KMC Z51 7 speed
Chainset: Suntour Triple 48/38/28T
Frame: Aluminium MTB style
Front Brake: Tektro V Brake
Front Hub: Formula, Alloy
Front Mech: Shimano FD-M191
Gear Shifters: Shimano Trigger shifters 7 speed
Grips: Carrera Comfort grip
Handlebar Type: Flat
Handlebars: 660mm, 25.4
Headset: Integrated 1 1/8"
Pedals: Wellgo Alloy Flat
Quick Release Front Wheel: Yes
Quick Release Rear Wheel: Yes
Rear Brake: Tektro V Brake
Rear Hub: Formula, Alloy
Rear Mech: Shimano Tourney 7 speed
Rims: Aluminium with CNC sidewall
Saddle: Carrera Components Comfort Saddle
Seatpost: Carrera Components micro adjust seatpost
Stem: Carrera Components alloy stem, 25.4
Type: Hybrid Bikes
Tyre Size: 27.5" x 2.125
Tyres: Semi Slick Urban Pattern