Floor heating and radiators happily work in conjunction with one another, to achieve this you will need to ‘T’ off from your boiler primaries, so one set of flow and return will go towards your radiators and the other to your floor heating system. Your heat source (boiler / heat pump) will still be producing hot water for your radiators, the same temperature water will be blended at the UFH manifold by a mixing valve. So while the heat source is still producing ‘hot water’ the UFH system ensures that you need less of it – saving you energy and money.
Any competent plumber can easily do the work for you to commission your heat source (boiler / heat pump) to both radiators (commonly upstairs) and underfloor heating (commonly on the ground floor).