There are plenty of destinations in the south reachable by train. I assume you'd like to make the journey in a day ?

I'd recommend booking the Eurostar ASAP, especially on busy dates such as half-term. Reservations cost 30€ and there is a Interrail passholder quota… But as regular tickets are expensive, a pass is pretty much always good value.

After Eurostar things are easier, don't worry.

If you'd like to avoid the annoying change of stations in Paris, I'd suggest taking the Eurostsr as far as Lille and then switching to a TGV direct to the south (Marseille or Montpellier basically). Another option could be taking a night train from Paris either to the Spanish border or to Nice.

If you let me know your travel dates (+ number of travellers) I could suggest good itineraries and/or destinations. :)

Bristol to London then across to somewhere sunny and quietish. We have been so used to a quiet resort in Algarve and love Portugal coastline. Also easy access flying but now with a teen who won't fly and doesn't like crowds and me thinking there must be a better sustainable way I'm looking at the train. We have 10 days around 20th October. If not viable this year we'll plan for next spring early summer. 2 adults and a 15 year old

From Bristol by train, Northern Spain (Barclelona) is a full day’s travel. Further south will require an overnight en-route and Portugal is particularly slow due to the rubbish cross-border connections with Spain.

You probably need to decide where within reach you would like to go (if anywhere is suitable as you seem to want hot weather) and then look at travel options.

Seat61 website has good travel options by rail from UK so perhaps look at that and the schedules.

https://www.seat61.com/

Your other non-fly option would be to go by sea, Brittany Ferries have routes from Plymouth and Portsmouth to France and Spain https://www.brittany-ferries.co.uk/

The South of France has good weather at this time of year I'd say, either on the Riviera (Nice, Cannes, Antibes) or in Languedoc-Roussillon (Montpellier, Nîmes, Perpignan). North of Barcelona is also not far away. Further south will need an overnight somewhere.

You could leave Bristol really early on Saturday or go to Lille on Friday night and continue the following morning. Remember that you can only use the Interrail pass in your own country on 2 days.

Saturday 21st October :

- Bristol - Paddington 05:30 - 07:07 or 06:05 - 07:36

- Tube (not included) or Elizabeth Line to Farringdon + Thameslink (both included), passport controls

- Eurostar London St. Pancras - Lille-Europe 09:01 - 11:26 30€

- lunch there

- TGV Lille-Europe - Marseille-St-Charles (for example) 14:03 - 18:44 20€

Friday 20th October :

- Bristol - Paddington every 30 min

- same as above

- Eurostar London St. Pancras - Lille-Europe 15:04 - 17:26 or 19:34 - 22:00 30€

And the following morning

- TGV Lille-Europe - Montpellier St-Roch 09:03 - 14:03 20€

Seat reservations prices in bold.

In any case book the Eurostar quite soon, it is a very popular route and some trains are already sold out for that half-term weekend. If you can leave any other day than Saturday there would be plenty more options.

Start your journey in Bristol and take a train to London. The journey takes approximately 2 hours. Spend the afternoon and evening exploring London's attractions, or consider an overnight stay.

If you stay overnight you will use both the outbound and inbound travel days so if you plan to take the Eurostar also back to the UK you must buy the ticket from Bristol separately.