Treat each cavity as a separate oven with its own door, seal and racks. Clean them one at a time rather than working across all of them, so cleaner is not sitting on one surface for an hour while you are elsewhere. Doors on the wider models are a two-person lift.
Belling makes range cookers, which means one appliance in your kitchen is doing the job of two or three. It is a Glen Dimplex brand and shares a great deal with Falcon, its premium sibling.
The whole difficulty with a Belling is the plural.
Count the cavities before you start
A Belling 90cm is usually a main oven plus a smaller second cavity or a separate grill compartment. Wider models add more. Each has its own door, its own seal, its own racks and its own runners, and the racks are frequently not interchangeable between them.
Photograph the layout before anything comes out, because a rack from the second oven will not sit properly in the main one and working out which is which afterwards is surprisingly difficult.
Then clean them one at a time. The temptation is to spray everything and work across, but that leaves cleaner sitting on one cavity for an hour while you deal with another, which is how enamel gets over-exposed and how you lose track of what has been rinsed. Our oven cleaning guide covers the method for a single cavity; do it three times rather than once at triple scale.
The second oven nobody uses
There is a consistent pattern on range cookers. The main oven does everything, and the second cavity gets used at Christmas and for nothing else.
What that means is that the second oven is either almost clean or carries a single catastrophic event from four years ago that has been baked by every subsequent use of the appliance around it. There is rarely anything in between. Open it before you plan the job, because it changes how long the whole thing takes.
The grill compartment is the same story and is the one most often skipped entirely.
The doors
Belling doors on the wider models are heavy and multi-glazed. Treat anything on a 90cm or wider range as a two-person lift, release both hinge locks before attempting it, and never let a hinge close on itself, because the springs carry serious force.
Keep every spacer and screw in order. A multi-glazed door will not seal if one goes back in the wrong slot, and a door that does not seal costs heat on every use afterwards.
Glen Dimplex, and the Falcon connection
Belling and Falcon are the same group, with Falcon above Belling on price. Components and manuals frequently cross-reference, which is useful when documentation for an older Belling is thin. See also how to clean a Belling cooktop, which on a freestanding model is part of the same appliance.
Freestanding means the hob is part of it
Most Belling range cookers are freestanding, which means the cooktop on top is not a separate appliance sitting in a benchtop. It is part of the same machine, sharing a fascia, a set of controls and frequently a single set of trim rails with the ovens below.
That matters in two ways. It changes how the appliance is priced for a professional clean, because a freestanding Belling is a stove rather than an oven and is quoted accordingly. And it changes how you clean it yourself: cleaner sprayed into a cavity runs down over the door edge and onto the fascia below, and on a range cooker that fascia carries the controls for everything.
Spray onto the cloth rather than into the oven. It is a small habit and on a multi-cavity appliance with a full-width control panel it is the difference between a clean and a set of faded markings.
What actually goes wrong
A second cavity nobody opened until the job was already quoted.
Racks returned to the wrong oven.
A door that no longer seals, from a spacer in the wrong slot.
One person lifting a wide door, which is how doors get dropped and hands get hurt.
Should you do it yourself?
Do it yourself for a single cavity with light soiling, working one oven at a time.
Get someone in if the doors need to come off, if the second cavity has a four year old event in it, or if the range is 100cm or wider.