Do you mean pre-Roman Britain (ie, prehistoric), Roman Britain, or post-Roman Anglo-Saxon England (before its conversion to Christianity)?
For all of these periods (from which very few written documents survive - except, of course, during the Roman empire), it's very difficult to talk about sexual norms. Who you prefer to have sex with doesn't often leave material traces in the archaeological record, so there's often no evidence whatsoever from which we can guess at people's sex lives or how they fit into a wider social context of acceptance / taboos.
We do have a few hints from 'pagan' Anglo-Saxon period (roughly 400-600) burial practices. In the cemeteries that have been excavated, most bodies were buried in separate graves. Sometimes, however, several bodies are placed in the same grave cut; often they're of opposite sex and look like a married couple who happened to die at the same time, or with an age difference that suggests a parent / child relationship. A woman buried at Butler's Field, Lechlade, has a young child cradled in her arms, and it's supposed that they were a mother and child who died at the same time. Or perhaps they weren't related and just happened to die at the same time, and the community burying them wanted the dead child to have someone to look after it. Barring expensive (and unreliable) DNA testing to see if they were actually related, it's largely guesswork.
In a few cases, we have people of the same biological sex buried together in the same grave. There could be a lot of different ways to interpret these burials (brothers, friends, or the simple inconvenience of digging two separate graves when two bodies might happily share the same grave). But in at least one case, the bodies of two men were buried embracing each other (Dover Buckland, see Evison 1987 ^1 ). We these men close friends who were buried in each other's arms to comfort them in death? Were they homosexual lovers who died from the same event (likely, disease), and were buried together as they lived? Did the person burying them dislike them, and buried them to look like homosexual lovers because that was an insult? Was one of them transgendered (male or female clothing is very difficult to see archaeologically, unless the body was wearing sex-associated metal objects like female jewelry)? Without the ability to interview these people, it's very difficult to say what the reasoning was. But it's very possible that these two men did have some kind of love for each other (whether sexual, or just a strong friendship), and that that love was honored in their burials.
^1 Edit: I thought it was Dover Buckland that had the embracing men, but I checked and it's not (though there is a grave in Dover that the site report interpreted as a possible homosexual couple - though see my cautions about this kind of interpretation above). I'm currently unable to track down the citation for the embracing male couple; I'll have to see if I can turn it up when I get back to the library, I know I saw it recently.