Do NOT Buy A Gravel Bike Unless You Have A Use For It
If you live in places like the UK you will be limited to what you actually gain from owning a gravel bike. For starters, there are not that many fire roads or good quality off road areas to go cycling with a gravel bike.
If you do not have much single track it is pointless buying a gravel bike. You will not get full use of it. I come from the North, near Wigan and the nearest place for me to use a gravel bike to its full was Rivington pike.
This was a 10k ride on roads just to get there. Yes, you can find the odd back road but even then you still get a number of cars on them which can make them quite dangerous on blind bends.
I also had a small forest section close by, but this was also used by many walkers and dog walkers. They are not perfect for gravel riding.
The other option which is great is the canal paths. You can find that some people will not move from their position when you are trying to pass them. Due to the amount of people now riding on canal paths be very careful when you pass someone.
On a good dry canal path, a road bike with 28mm tyres will suffice. I know as I have done it. But in the UK where it rains a lot, these paths can be difficult, crowded and become boring.
You may be better just using your hardtail mountain bike and doing what many others have done. Fit a set of 34mm smooth tyres and enjoy the gravel paths and road at the same time. Plus you will save yourself the money from buying a new gravel bike, only to find that it seems to be on the tarmac road most of the time.
The UK does not have that many great off-road routes designed for gravel bikes, which is a shame considering the number of cyclists there. To find them you can do a simple search online for gravel tracks in your area.
There will be more in the North of England and a few in places like Dartmoor and the hills in Somerset. Anywhere where there are mountains should provide a few decent routes, but do not be surprised by the lack of quality for gravel riders.