Everybody should become a Christian, and if you aren't you should do it today - do it now.
But - at least initially - become a Christian first, and don't leap into joining a church.
Obviously, this does not apply if you believe that only one church is THE Christian church - but few Christian's truly believe that.
The problem is that at least 90 percent of actually-existing self-styled Christian churches are anti-Christian in overall tendency and effect - Anglican, Catholic, Methodist, Presbyterian, Baptist etc.- typically, they all lead their flock astray.
Indeed, all the large, powerful mainstream churches in the UK are - at their senior levels especially - primarily 'front' organisations for Left Wing politics - Christianity is merely a rationalization for their primary agenda of political correctness.
So, why join a church that will try to make you a worse Christian, or not a Christian at all?
Even among the (say) ten percent of real Christian churches, at least half will be unsuitable for you personally, for one reason or another.
Either they will be just not-helpful, or so alien and unappealing that it will be a constant battle merely to attend, to engage and to stay active.
At a conservative estimate - if you become a Christian and join a church then there is a ninety-five percent chance that church will not help your new faith, or will actively try to erode it.
Clearly, it is much the best thing to be inside and engaged-with a real Christian church - but that is much easier said than done.
Therefore the safest strategy in the UK is to become a Christian in haste, but to be slower and very careful about choosing a denomination; or else you will likely have cause to repent at leisure your precipitate act of premature church membership.