Two questions:
If you might need to liquidate your funds quickly, why are you considering stocks and shares? I invest in a stocks and shares ISA and take a minimum time-frame of 5 years and drip-feed in the money in order to reduce the risks involved. This has given me a good return over this time period but with many sharp falls along the way. If you can take a longer term view then the exact timing of your investment may become less important. If your view is short term then your cash ISA is a wise move.
Secondly, why a managed fund? Have you considered a simple tracker fund where the costs are often much lower? Many managed funds actually under-perform these simple tracker funds over time, not least because the computer programme running the fund doesn't want to drive a Porsche.
Have a look at this (and apologies if I'm pointing out stuff you already know):
http://www.fool.co.uk/isas/information/wha...ex-tracker.aspxTime and consistency are the two friends of the risk-averse investor. Short-term speculative moves are best left to those with exceptional knowledge and/or luck or should only be done with money you can afford to lose.