I'm pretty sure the way NHS dental care works in the UK is basically broken and I'm not sure I trust any dental practice which relies solely on NHS income. Let me tell you why:
This can be a bit fuzzy and I may make a mistake here or there but I think the gist is still very correct. A few years ago I used to work for a company which wrote dental practice management software, so I got a good idea of how NHS dentistry works. The way you get paid doing NHS dental care is you sign a contract with the dental board on which you tell them the estimated number of Units of Dental Activity (UDAs) which you expect to carry out during the year. You get penalized upon contract renewal if you miss this target by too much. All work done on an NHS patient is broken up into Courses of Treatment (COTs) and each COT has a band given to it. The band is based on the treatments which were performed as part of a COT[1], most importantly, if you perform two fillings instead of one, the band does not go up. Each band gives a different number of UDAs[2]. You can't start a COT too early after a previous one (2 month rule)[3] unless it's a higher band.
Due to these factors, two things appear to happen:
1. Very obvious, NHS dental practices will refuse new patients even if they have the capacity to accept them because they expect they will already match their UDA count for the year. I don't think any of them will explicitly tell you this reason but it happens all the time in the UK, the key word is they will tell you to call around April (which is when contract renewals happen).
2. Less than trustworthy dentists will, upon spotting e.g. a cavity starting to develop and a bigger cavity in another place, fill the bigger cavity and then address the smaller one at your 6 months checkup to avoid stacking the COTs and losing out on additional band 2 UDAs.
Very much not saying that all nationalised dental health care is shit, but in the UK I have generally had better experience with dental practices which do mixed care than dental practices which solely focus on NHS dental care. Don't be like the UK.
Yes, the UK doesn't have nationalised dentistry. It's private practices which take money from the NHS. I'm advocating for full nationalisation: dental practices, optometrists, and GP surgeries all being fully run by the NHS, not by private companies/individuals.