BMW R1200RT/R1250RT Forum

I’ve just read an article about this Smart Sim that can be configured to kick in when you haven’t got a signal on your network, and allows unlimited data access to use other networks on certain apps (they say 500+) but not voice calls, media nor texts. It also covers unlimited data use in 180 countries.
It looks like all that for £45 annually or £10 a month.

I’m probably screwed up the description but here’s the link -

https://join.honestmobile.com/smart-sim-review

I don't know if you can get Google Fi in the UK, but if you can, your problem can be solved with 1 SIM and probably cheaper. Worth looking into.
I have been very happy with Fi for the past 5 years. It works seamlessly in @ 140 countries.

Sounds good. Here’s what Google AI says -

Google Fi does not offer direct, official plans for purchase within the UK, but UK residents can purchase and use compatible SIM cards from third-party retailers like Amazon UK. These SIMs allow you to use Google Fi's service, but service availability, data speeds, and international roaming rates will vary depending on the plan you choose.

How to get Google Fi in the UK:
Purchase a SIM kit: You can buy a Google Fi SIM kit from a third-party seller, such as Amazon UK.
Set up the app: Download the Google Fi Wireless app and follow the on-screen instructions to set up your service.
Choose a plan: Select the plan that best fits your needs, such as the Flexible or Unlimited Premium plans.
Use your phone: Once you have signed up, you can use your phone to make calls, send texts, and use data in the UK and over 200 other destinations.

Things to consider:
International roaming rates: Google Fi's international roaming rates may vary depending on the plan you choose. Be sure to check the rates and data allowances for your plan before traveling to the UK or another country.

Network coverage: Google Fi uses the T-Mobile and US Cellular networks in the United States, so coverage in the UK will depend on the partner networks available in your area.
Data limits: Some plans may have data limitations or a slower data speed after you exceed a certain amount of data usage.
Device compatibility: Google Fi supports a wide range of Android and iOS devices, but some features may not be available on certain devices or operating systems.

Third-party retailers: Google does not have its own physical stores in the UK, so you will have to purchase a SIM card from a third-party

Unfortunately Amazon UK don’t appear to sell it.

I bought a SIM-only. IRC Lebra. I stopped last year as i didn't need it anymore. It didn't have any free calls but came with 10GB of free data. The cost was £7 per month.
You can find cheap data SIMs, but you have to look around. Smarty, Lyca, LD Mobile, and Lebara most under £ 10 for 10GB per month.
Lebra do 30gb for £10pm with no contract. unlimited UK calls and 100 minutes of European calls.
I used an old phone to use for Google and Waze mapping

Smarty Sim £10.00 for 80GB PCM on the Three/Vodafone network