UKC

I’m trying to price a train ticket from Penrith to Albertville , is this possible to do as one ticket or do I need to do Eurostar London to Paris and so on all separately?

You can buy st pancras to Albertville as 1 ticket.  Buy that then get a connecting ticket to London 

Man in seat 61 website has good advice on this- I believe you can buy the UK connection at the same time which means if your UK train is delayed or cancelled you still get a Eurostar seat even if you missed your connection. I can't recall the details but definitely got it from that source.

Also look into a interailpass. You'll have to pay a supplement for the Eurostar, but prob works out cheaper.

Interail can be great and will probably be the cheapest option if travelling all the way from Penrith.

As I start further south I now tend to book  tickets for travel within Franc on SNCF connect where some great deals can be found if you are flexible. At present I do the London to Paris Leg by overnight bus, if you pick a bus that uses the right ferry company you usually get a free meal on the ferry.

Be aware that rail operator websites don't always get all inter-country options. For example, if you look up a trip from France to Germany with the Trainline and Deutsche Bahn you will see some options on both, but not all.  You may also be told an overall journey isn't possible, but by splitting it up into sections it is. I regularly travel from Normandy to Bavaria and often cannot get a price for the whole thing yet can get one ticket that gets me to Paris, then another that gets me from Paris to Bavaria.