The Eurail pass has been valid in the UK for a number of years now. Brexit hasn't changed anything and is also unlikely to have an impact on validity because pass usage and pass validity are not related at all to EU membership.
No worries about using the pass in the UK. It’s an absolute pleasure to use the pass in the UK. You can use it on almost all (mainline) trains. Brexit changed not a thing for that, luckily.
Some advice before you plan:
- The rail planners of Interrail (especially the app) are not very reliable, since it doesn’t get a lot of updates.
- Eurail is not necessarily the cheapest option, especially if you only do a couple of trips. Always compare with advance ordinary tickets on the train operators’ websites, it can be quite cheap but you will be less flexible than with a pass.
- A lot of trains in Spain require mandatory seat reservations. So you need a pass + a seat reservations. A seat reservation comes with an extra cost (varying on the train you take, but no more than 10 EUR per seat per train in 2nd class.)
- Spain is considered as a difficult interrail country, with lot of mandatory reservations, that you cannot reserve online. There are better countries to use your pass (like the UK, Benelux, Germany, Austria, Switzerland,...)
- You might want to look in the “Renfe Spain Pass” there if you plan a lot of travel in Spain, as all reservations are included in that.
- Rail connections Spain-Porugal are bad and limited. Quite adventurous, especially for the unexperienced railer.
- But don’t be scared of this all, it’s a fantastic way to travel, and much more relaxed than any other mean, once you get the hang of it.
As an Australian, you’re probably very unfamiliar with (International) train travelling and public transport.
Before planning, booking or buying tickets, I advise you to inform you a bit more. For more info best read the man in Seat 61, a real goldmine for information if you want a good overview: https://www.seat61.com/european-train-travel.htm
And the country specific pages:
https://www.seat61.com/train-travel-in-britain.htm
https://www.seat61.com/Spain.htm
https://www.seat61.com/Portugal.htm
Please note that timetables for Septembre/Octobre on the year are probably not available yet. 2-3 months before, most should be online. But Spain can be late with sending it’s data, so sometimes it’s only a month before.
Once you get your head around all of this, feel free to ask us on the community for advice. We won’t do the planning work for you, but if you can’t get your head around something, or have difficulties with finding the right information or tickets, we’re happy to help.
The more details (exact date, time, destinations,...) the better we can help.
Thank you so much, I will definitely look in this before doing anything this has really helped.