Hi,
There's many people who are recent immigrants into the UK who have opened up a business, the thing is, there's varying 'levels' of what you are asking. Do you mean a micro business? small or small to medium (SME) size business ? are you thinking of something very specific? Business to Business (B2B) or Business to Consumer (B2C)?
There's multiple aspects and factors to each, ranging from Tax and accounting planning, to type of business (sold trader/limited company/umbrella company if you might be contracting, home based, require premises, licensing and so on...
My background is a mixture now, have worked for 3 USA Financial IT companies (most recognizable being Intuit - makers of Quickbooks & TurboTax. Quicken was theres but was sold to another company a few years ago) and also being involved in a family business with 30-35 staff and also my own micro company. What kind of business sector are you thinking of? I do have some good contacts and/or pointers for you including family members and friends along with ex colleagues and other acquaintances with their own companies. Happy to help if I can !
Cheers, DtM! West London & Slough UK!