The Status omnidirectional mushroom needs a strong signal to work properly. The Status directional aerial is a log periodic type and is very good at rejecting unwanted signals / interference but still needs a fairly good signal.
Maxview do a 25dB amplifier which can be used in series with any aerial including the two Status - this will improve things somewhat.
Strong signal areas are limited so you need to be fairly close to a transmitter for either Status to work effectively.
Most of the UK is some distance from a transmitter and really an amplified extra gain aerial is needed. These have elements like X's, the more elements the better. These extra gain aerials aren't heavy but are bulky for caravanning.
Digital TV needs a higher signal strength. The analogue switch-off starts in 2008.
Some better equipped sites, ie more expensive, have installed an aerial booster system with an aerial point at each pitch.
An alternative is a satellite system, ie a full Sky subscription, Freesat from Sky or the upcoming Freesat from ITV/BBC.
It comes down to personal choice - how important is TV to you when caravanning. This will determine how much you need to spend on equipment and time spent erecting / aligning it!