Apologies for not having taken a photo at the start. Just think ‘junk’ and you won’t be too far off. All photos below are of the restored model.
I began by soaking it in oven cleaner for two days, wrapped in a plastic bag (the model, not me). That got rid of most of the old paint, though some further work was needed to remove it all.
I sanded down the slightly raised panel lines and used a sharp point to scribe new ones. Although I followed the raised lines on the wings, the lines I scribed on the fuselage were more random. I don’t worry that all panel lines should be visible in 1/72 scale.
I made a new flight deck interior with an instrument panel, seat and some side panels. I painted and added a pilot figure to help fill the space.
I used the starboard engine nacelle as a template to make a new port one. That was made from 20 thou. plastic card that I dunked in boiling water to get the right shape. The front piece was cut from a nacelle in the spares box and trimmed to fit. The result is a port engine that is slightly bigger than the starboard one, but hopefully not too noticeable. I suppose I could have enlarged the starboard one by wrapping plastic card around it, but if I did not tell you, would you have noticed?
I drilled out the engine moulding from the starboard engine and replaced it with one that had better definition from the spares box. I also raided the spares box for an engine for the new port nacelle.
I scratch built the undercarriage legs from scrap sprue and wire. The wheels came from the spares box. They may not be entirely accurate, but they seem to look about right. I suspect that the sit of the model is slightly too high, but it’s not too bad.
I made a flight deck and observer’s transparency by carving some balsa and using it to plunge mould the replacements. I did that using 20 thou clear plastic card. The observer/gunner’s machine gun came from kit parts.
I cut notches in the wing tips and inserted pieces of clear sprue to represent navigation lights. These were sanded down to lie flush. I also added some stretched sprue to represent the rear facing wing tip lights. And yes, I know there are no landing lights in the photos – I forgot to include them during the build, but I added them after the photos were taken.
The engine exhausts were cobbled together using various spare pieces, marrying the saw tooth ends to the front pieces.
The rear wheel was made from wire and a spare small wheel from spares. An aerial was made from scrap plastic. I drilled out the four gun ports under the fuselage.
The model was painted using Humbrol acrylic paints. The decals were cobbled together from odds and ends. I got some ‘dust’ by rubbing some pastels on sandpaper and dabbed the dust onto some of the panel lines. I added decals from spares then gave it a coat of Revell Aquacolor matt clear varnish. To finish it off, I rubbed some light grey pastel chalk onto some sandpaper and applied the dust to the model. This was intended to give it a dusty desert-like appearance. It may just make it look messy!
And that was it. Memo to diary - I really must buy the new Airfix Beaufighter one day.
I am in envy of your scratchbuilding skills, and also of your spares box -- mine only ever seems to have a few weapons and a ton of undercarriage parts in it (I make my aircraft models in flight, and hence with their gear up). 
