No reason to clean it up first; go ahead and post your "before" pics. The model name would have been on the top tube but those decals seem to be quite fragile. Replacements are likely available through H LLoyd's in the UK.

I'm going to guess that you have an Aerospace GP. Your guess on the year seems about right, too.

And, most of us Viscount owners are missing at least one pedal dust cap. I know I am.