Hi and welcome.
Forget 'I,m not that good with spanners'! Cafe racers are actually not that difficult, let's face it, the average spotty-faced 1950's/60's greaser was not likely to have a degree in engineering. They took their Dad's 'ride to work' and turned them into a life-style.
You are looking at taking a stock bike of some sort and turning into something individual, no hard and fast rules, it doesn't have to be a Triumph Bonnie engine in a Norton 'featherbed' frame, I've seen some stonking 125s and some amazing Japanese multis, Harley's, BMWs, twins, triples, the limit is your imagination! Google cafe racer and see what's out there.
The first place is the handlebars, ditch the sit-up-and-beg high rise bars for a set of clip-ons or 'ace' bars, Now you are leaning forward over the tank, race bike style, but your knees are under your chin, so you need a set of rear-set foot controls so you are more comfortable and aero dynamic, lying along your bike in true 'race' style.
Next, body work, do you need a twin seat? If so get one with a bump stop or tailpiece to stop your 'bird' sliding off the back as you accelerate! A nice tank with indents so your handle bars don't hit it on tight turns.
How old is your bike, are indicators really necessary (rhetorical, they are compulsory after a ceratin year.)
Different side panels, paint, exhausts, tuning, you've got a cafe racer, as individual as your mind wants to make it, no rules!