They all offer inclusive roaming. Something we were supposed to lose when we left the EU.
Most of them require the purchase of one of the plans.
A very few offer inclusive roaming.
The argument was always that roaming would not be free anymore, after Brexit.
Now 8 years after Brexit there are one or two providers offering to provide free roaming for an unlimited time.
most are time limited, and once roaming is withdrawn, they require an extended period (sometimes 3 months) back in the UK before roaming is again available.
I wouldn't call that a Brexit bonus. Many people have paid additional fees over the last few years. Others have had to search for a work-around.
I have an old phone which can't accommodate multiple SIMs, so I use a device from SIMore which accommodates the use of up to 4 SIMs.
Three in the SIMore device and one in the actual phone.
if your phone accommodates multiple SIMS, the easiest and cheapest work-around is an additional local SIM.
BUT, ensure the provider will continue to provide the service when they become aware that you are using multiple SIMs in your phone.
They may ask for ID evidence to protect themselves.
The use of multiple SIMS and/or multiple phones is a practice employed by criminals.