In the US we can use LabCorp and self-pay if you really have to. In the UK you actually have several private blood testing options available that don't require NHS or GP involvement at all:
Randox Health – Charlotte already mentioned them upthread, and they have 40+ clinic locations across the UK and Ireland. No GP referral needed. They offer comprehensive panels that include oestradiol, testosterone, SHBG, prolactin, liver function, and FBC — basically everything Nottingham's letter specifies for monitoring. Charlotte's tip about the discount code is worth noting. Their home test kits start from around £21-69, while in-clinic health check packages start higher at £139+.
Medichecks – Another well-established option that offers both home finger-prick kits mailed to you and venous draw appointments at partner clinics nationwide. They have hormone panels covering the same biomarkers. The Gender Hormone Clinic specifically recommends their TRT Check Plus panel for trans patients. Important note: if you're on any gel-based hormones, they recommend venous draw over finger-prick to avoid contamination from residue on your hands.
Lola Health – A newer service that also offers home visits from a phlebotomist, which is convenient if clinic access is difficult.
For our London-based members, 56 Dean Street runs 56T, a dedicated trans and non-binary sexual health and wellbeing service every Wednesday (4:30-7pm, Level 2, appointment only) that includes hormone blood testing and injection services.
CliniQ at King's College Hospital runs a similar holistic service for trans and non-binary people every Tuesday (4:00-6:30pm, Caldecot Centre, by appointment). Both are primarily sexual health services but include hormone level monitoring as part of their care.
The results from any of these can be sent to your specialist — Nottingham's letter specifically says they'll interpret blood results forwarded to them and adjust the care plan accordingly.
None of this should be necessary. The fact that the NHS is blocking routine blood monitoring for established patients is genuinely dangerous, especially for people who are post-orchiectomy or oophorectomy, and have no endogenous hormone production.
At least these options exist as a stopgap while the bureaucratic battle plays out.