Like "Gentlemens' Clubs", shouldn't restrictions based on your genitalia be illegal?

No, that would be far too all-encompassing. I would for example object extremely vigorously to any attempt to prevent me restricting who I am willing to have sex with based on their genitalia. And while I'm quite aware that some of the population don't feel the need to apply such a restriction, I'm pretty sure that a considerable majority would be with me about wanting to apply such a restriction - though of course with differences about exactly which restriction they would want to apply!

The laws concerned quite rightly (IMHO) only prohibit sexual restrictions for some purposes. E.g. the Equality Act 2010 classifies the purposes concerned broadly into Services & public functions, Premises, Work, Education and Associations in its main parts, and has numerous special rules and exceptions in each of those categories. To quote one that looks relevant to TMF's provision of TPR and TLR, here is section 26 of schedule 3 of the Act:

"26 (1) A person does not contravene section 29, so far as relating to sex discrimination, by providing separate services for persons of each sex if—

(a) a joint service for persons of both sexes would be less effective, and

(b) the limited provision is a proportionate means of achieving a legitimate aim.

(2) A person does not contravene section 29, so far as relating to sex discrimination, by providing separate services differently for persons of each sex if—

(a) a joint service for persons of both sexes would be less effective,

(b) the extent to which the service is required by one sex makes it not reasonably practicable to provide the service otherwise than as a separate service provided differently for each sex, and

(c) the limited provision is a proportionate means of achieving a legitimate aim.

(3) This paragraph applies to a person exercising a public function in relation to the provision of a service as it applies to the person providing the service."

Gengulphus