LONDON — The spectacular performance of “Toy Story 2” pushed U.K. cinema admissions in February to their highest monthly figure in 29 years.A total of 3.98 million tickets were sold. The fact that February is the shortest month only makes that achievement more notable. “Toy Story 2” grossed £32.9 million ($52.6 million) in the month, trailed distantly by “American Beauty” with $18.5 million. Official estimates from the Cinema Advertising Assn. already suggest that March admissions will be up 5% over the same month last year. This confirms that U.K. cinema-going is firmly back on the upswing after hitting the doldrums in the first half of 1999. Ticket sales have risen every month since June, with the exception of September.