I use shimano m520 MTB spd pedals on all my bikes, you can pick them up for £15 without cleats as i have fair bit of walking and prefer them for that over "road " cleats that sit on the outside of the shoe making it harder to walk .
Road pedals for the shoes you like generally ha've a triangular cleat , decathlon do these ...
http://www.decathlon.co.uk/delta-compatbile-pedals-id_8173122.html
Both systems have their merits and pitfalls , some say you get a bit more power transfer with the road pedals as thye have a bigger cleat but i have ridden with the smaller mtb spd for years , including on cycle club runs and i have never had a problem with them .