Put both regexes into a non-capturing group separated by an alternation operator |.
^(?:((07|00447|\+447)\d{9}|(08|003538|\+3538)\d{8,9})|((0|0044|\+44)\d{10}|(08)\d{9}|(90)\d{6}|(92)\d{6}|(437)\d{5}|(28)\d{6}|(37)\d{6}|(66)\d{6}|(82)\d{6}|(777)\d{5}|(93)\d{6}))$