I have no idea whether or not FitnessFirst gyms are any good but a free 8-day pass sounds OK to me. Normally free passes are for shorter periods. I expect there will be some high-pressure sales pitch at the end of the trial but you can always say NO!
"To activate this offer and find your nearest club call 0844 571 8080. You’ll receive a 8-day guest membership and beach body analysis. We’re good to you, aren’t we? Your guest membership is valid at all Fitness First blue and platinum clubs. Our Black Label clubs are exempt from this offer but you can still pop in for a tour and to discuss your personal fitness goals. During your guest membership you’re welcome to use the sunbeds, beauty rooms and crèche for an additional charge. To check your local club’s facilities visit fitnessfirst.co.uk And now for the legal bits: You must be 16 or over; the offer is subject to availability*; your 8 days at the club must be consecutive; this voucher has no cash value, is not for re-sale and the offer is valid to 16th June 2011. And most importantly…you’re gonna love it"