East London Out Project (ELOP) provides a range of services for lesbian, gay, bisexual and trans people.
London Friend https://londonfriend.org.uk/ Charity offering counselling, drug & alcohol service, social support groups, sexual health advice, to the LGBT community.
The London Lesbian and Gay Switchboard is helpline and information for gay and lesbian people.
The Pink Practice is a lesbian and gay counselling and psychotherapy service based in central London.
Imaan is a social support group for lesbian, gay, bisexual and transgender Muslims, which offers advice and support through their website.
If you identify as trans or non-binary, MINDLINE TRANS+ offers a helpline to offer support when you need it. The number is 0300 330 5468.
The line operates Mondays and Fridays, 8 pm to midnight and is run by trans volunteers
Transgender Support Groups lists support groups by area both in the UK and elsewhere in the world.