“…an application to strike out in the FTT under rule 8(3)(c) should be considered in a similar way to an application underCPR 3.4 in civil proceedings (whilst recognising that there is no equivalent jurisdiction in the First-tier to summary judgement under Part 24). The Tribunal must consider whether there is a realistic, as opposed to a fanciful (in the sense of it being entirely without substance) prospect of succeeding on the issue at a full hearing…The Tribunal must avoid conducting a “mini-trial”