Underground station car parking

Hi all,

Can anyone advise what my likelihood of getting a space at one of the Underground station car parks (or Waitrose at Rickmansworth) if I turn up tomorrow morning at about 9.30am?

I've found a report on the TfL website which is over two years old which seems to suggest stations to avoid

''Redbridge (peak 99% occupancy at 8am and has 147 car parking spaces); • Newbury Park (98% at 8am – 459 spaces); • Theydon Bois (98% at 8am – 65 spaces); • Cockfosters (98% at 5pm – 430 spaces);
• Buckhurst Hill (97% at 8am – 120 spaces); • Eastcote (96% at 8am – 50 spaces); • Hounslow West (94% at 5pm - 425 spaces); • Loughton (93% at 5pm – 288 spaces);
• Debden (92% at 8am – 190 spaces); • Arnos Grove (91% at 5pm – 306 spaces); • Colindale (90% at 5pm – 21 spaces).''

And those with a good chance of getting parked:
''• Chorleywood (maximum 49% occupied, peak at 5pm and has 238 car parking spaces);
• Hillingdon (43% at 8am – 283 spaces); • South Harrow (42% at 8am – 73 spaces); • East Finchley (37% at 8am – 267 spaces).''

But conversely I've heard Hillingdon is one to avoid.

I'd prefer somewhere near the M25 so Hillingdon fits the bill quite well, but perhaps somewhere in the North East corner would be a bit better?

I'd rather avoid BR stations if at all possible, but if anyone can recommend something on a direct line into Victoria that wouldn't be too bad.

Thanks!