Sportsbikeshop has got a bricks n mortar place in South Reading, not far from the m4 junction. Their online ladies selection is really good, although their instore offerings isn’t so great. So much depends on what she’s after - high spec race leathers or occasional weekend pilly riding etc.
On Yer Bike has a reasonable range of ladies clothing, especially considering the size of their premises, and the bike franchises there also have their own range.
My own fave place for new gear is ebay and pretty much my entire biking wardrobe has come via there, either through a discounted outlet or 2nd hand. And I have got A LOT of gear!