GP's in the UK are notoriously reluctant to prescribe benzodiazepines compared to many other countries (Eire, for instance where they hand them out like sweets), one primary historical factor being 'the largest-ever class-action lawsuit against drug manufacturers in the UK'
(link), which held manufacturers of the drugs responsible for withholding information from prescribers regarding the significant dependence potential of the drug class.
In many ways it is a good thing as those who are willing to issue new prescriptions tend to do so extremely responsibly, using them only in cases of severe mental distress and issuing them sensibly (either in short courses of 2 - 4 weeks or, for instance, in small amounts - my GP allows me to use diazepam 'as required' but never lets me have more than 4 boxes of 28 tablets over a 12 month period). Some GP's are more liberal than others of course but the majority tend to under prescribe them, when there careful use in certain situations would not be problematic so long as the Doctor monitors their use closely and does not prescribe any more than is required for no longer than they are genuinely needed.
However
Forgive me for jumping to conclusions den4 but the levels of anxiety you are describing may not yet warrant such powerful and addictive drugs (I am now completely unable to function if I do not at least have access to benzodiazepines should I need to take one) - you have not specifically stated that you have stopped using cannabis despite the bad experience after 'too much'.
You need to keep engaging and be honest with your GP and that is as much advice as we can give - we cannot 'tell you' what to say to your doctor or coach you in any way as this would be seen as helping you to obtain controlled drugs you may not actually need yet.
Why you are asking about opi drugs within this context is beyond me - they are not clinically effective or ever used for treating anxiety and your choosing to group them with benzodiazepines as a desirable treatment you want highlights you as drug seeker first and foremost
