As others have said, don't sweat it - you got on OK riding through Germany.

If you really want to save time, then I would stay out of the Alps and ride south within France, enjoying their highways which are so much more free of traffic compared with the UK - drop onto the motorways here and there when they are toll free and then back onto the national and departmental routes.
Most French towns have bypasses to skirt around them; the French highway authorities recognised a good idea from the UK quite a few years ago and they have now constructed loads of roundabouts - just get used to going around them the "wrong way" and become used to counting the exits counter-clockwise rather than clockwise.

At the bottom of France, turn East and enter Italy.

Just to elaborate a bit, what I say here is one of those "6 and two 3s" kind of answers.
Because you haven't said what time of year you will travel - for winter, there is little point in heading into the Alps except for the skiing.
In the height of summer, e.g. August, I try to avoid the Alpine areas (although I may be breaking that personal rule of thumb this year just to find out, yet again, why I have that rule of thumb in my mind).
Try the Sud Tyrol (German speaking northern Italy) on the way, if you do go via the Alps.

ps
From Blackpool you can cross the sea via Hull-Zeebrugge and that bypasses the M25 around London and the Dartford bridge.

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Dave