I believe so, yes.
Apart from the inconvenience of having to open the gas locker to connect to your bottle(s), I have heard of instances where garages have refused to sell gas to vehicles where the filling is done via open boot lids/lockers, etc. and not via a purpose-
fitted connector. This is presumably a caution against people attempting to refill bottles that are non-user refillable because they don't have the internal "80% shut-off" safety device (ie Calor, etc).
For the comparatively minor job of cutting the 70mm hole adjacent to the gas locker, the benefit is overwhelming. A garage repair shop could possibly cut this hole for you for a few quid if you were intent on doing the job yourself. I'd urge you to get the gas connections either made or at least checked by a qualified gas-fitter before you use the system no matter how competent you think you are. The gas fitter should carry personal liability
insurance should the unthinkable happen later (a disastrous gas leak, etc.).
When deciding the position of the hole, sufficient space on the interior is, of course, important. Have a dummy run on the floor of your garage (or lounge if Mum lets you!) so that you can visualise the space that the hoses' curves need on the inside, behind the connector.
If you do cut (or have cut for you) this 70mm hole, I'd caution you against using a DIY hole cutter, normally sold for use on wood. Some m/home walls use steel mesh embedded in the construction and/or have an aluminium shell - neither of these is suitable to be properly cut by a DIY hole-cutter. The proper cutter costs about 20 quid or so and a tradesman should either have one or be prepared to acquire one to do your job. If cutting it yourself with the correct cutter, apart from checking the position
several times(!)
before making the hole, I recommend that you cut part way through from one side and then finish the hole by cutting from the other side - you then have two neat cuts either side.
Good luck.
Barry