The combos with the LMII head in them tend to be somewhere between £500-700. You can pick up an LMII for @ £300 & if you want it to sound like an Ashdown, you just turn the VLE filter to full & roll off some treble if needed.
Soundslive are on Dean Street in Nookie. They stock Ashdown, Ampeg & Markbass, so maybe worth popping into there?